Computer-interfaced stopped-flow devices (absorbance and light-scattering), dye-laser and air-flash-photolysis devices are being used to study both ligand binding rates of oxygen and carbon monoxide to diverse hemoglobins and myoglobins and subunit aggregation and dissociation rates for oligomeric hemoglobins. Studies on co-operative dimeric hemoglobins and myoglobins involve determining rate constants and equilibrium constants for ligand binding and determining whether or not these data can be accommodated by various theoretical models (Adair, allosteric, Ising, etc.). The influence of solvent composition (mixed -solvent studies), temperature, and pH on ligand-binding kinetics as well as on subunit interactions is being explored.